High-power electron generating device



Dec. 5,1933. J BETHENQD 1,937,542

HIGH POWER ELECTRON GENERATING DEVICE Filed June 2. 1925 INVENTOR J. BETHENOD A ORNEY Patented Dec. 5, 1933 UNITED STATES HIGH-POWER ELECTRON GENERATING DEVICE Joseph Bethcnod, Paris, France Application June 2, 1923, Serial No; 642,946, and

in France June 15, 1922 13 Claims.

At the present time there is being used in electrotechnics, and more particularly in wireless work, a type of apparatus adapted to electron emission permitting more especially either the rectification of alternating currents of any given frequency, or else the productionof alternating currents of likewise arbitrary frequency, from a direct current, of high voltage.

All of these apparatus, as a matter of-principle, comprise a cathode raised to a more or less high temperature,,whose surface is the seat and source of electron emission and generation and thus constituting, as is well known, the basis underlying the operation in question. When an apparatus of high power is to be built, one encounters the following difficulty:

To raise the cathodeto the requisite temperature, this electrode is ordinarily given the shape of a filament heated by means of an auxiliary source of current; now, the 7 emanating per square centimeter surface area, of the cathode per unit of time (second) depends only upon the absolute temperature thereof, and if it shall not attain a temperature liable to cause rapid destruction of the device, it is necessary to make the cathode of large surface to the end of realizing correspondingly large power. It is quite I evident that the filamentary form is badly adapted to the purpose in question, and that it would be far preferable if ways and means were known to give the cathode the construction of a plate of any convenient cross-sectional shape, disc or cylinder especially.

However, then the direct electric heating of the cathode would become an impossibility, for obvious reasons, so that it is necessary todiscover another method of heating. Reasoning along these lines, the proposition has been made to give the anode and the cathode the form of two concentric cylinders, with the anode being are ranged exteriorly, to heat the cathode by virtue and means of radiation, more particularly by the aid of a spiral disposed interiorly thereof and raised itself to incandescence by means of an auxiliary source of current. However,

artifice would give only a rather limited improvement if proceeding along the lines stated, because it is known that the realization of a heating spiral or coil, if it shall be of great power and effect, will always be a delicate problem to solve.

Now, in conformity with the present invention heating of the cathode is ing it of a circular body, as a matter of principle, and so giving it an annular or circular shape, and in which currents are induced by the aid of an alternating magnetic flux conveniently arranged. The Joule effect thus produced in the very body constituting the cathode sufiices for raising it to the desired temperature.

By way of example, Figs. 1 and 2 herewith innumber of electrons ternating currents of any frequency at all, from such an 1 accomplishable by formdicate diagrammatically a number of embodiments of the invention that are particularly simple in nature. Fig.- 3 is a cross-section taken through the center of Fig. 1, and Fig. 4 is a crosssection taken through the center of Fig. 2.

' According to Fig. l, the'device consists essentially of acontainer orvessel 1 made of glass or of quartz preferably, possessing the shape of a torus. In the interior thereof are arranged:

A cylindrical plate 2 forming the cathode to be heated, this plate being made from a convenient kind of metal lined or covered, if so desired,'with metallic oxides (oxide of barium, etc.) to the end of enhancing electron emission.

Further, a second cylindrical plate 3 constituting the anode, and consisting, forinstance, of a thin tungsten sheet or strip.

, Finally, optionally, a third plate perforated by holes and disposed between the two chief elecftrodes 2 and 3, this latter, optionally provided, plate constituting the control electrode or grid well known in the art, the useful function of which hasjbeen demonstrated in certain services and applications, especially the. production of aldirect current of high voltage. l

Traversing from one end to the other of the torus-shaped container 1, there is arranged a closed magnetic circuit 5 built up of laminated iron, and through which passes an alternating magneticfiux created, e. g., by means of a winding 6 energized by an alternating current de rived from any convenient source at all. Under these conditions, cathode 2 which forms a closed turn,.thus constitutes the secondary circuit of a transformer, of which 6 is the primary winding. By appropriately dimensioning the various constitutive elements of the'device, it is feasible to raise the said cathode to the desired temperature quite easily merely byJoule effect. It must be noted, however, that anode 3 and optional control i must be provided with slits '7 di-' rected towards the generatrix of the respective cylinders, to the end'of limiting the Joule effect produced by 5 in the cathode 2. 1

-Moreover, according to the effect to be proe duced, the medium inside enclosure or vessel 1 can be chosen ad libitum; indeed, one can choose a vacuum ashigh as feasible, or one may, on the contrary, choose as such medium any convenient kind of gas, argon, or the like. Finally, as regards the constitution of the magnetic circuit 5 and the position of inductor winding 6, recourse may be had to various forms of construction; for instancamagnetic circuit 5 may-be'thatof a voltage transformer, for feeding. the circuit containing electrodes 2 and 3; It will be noted that for thesake of greater clearness and simplicity, the tapping or connecting points for the currents corresponding to the various electrodes are not by anybody experienced in the art. 35

. tainer and one of said being shown in the illustration since they do not represent any particular features in this case. Furthermore, anode 3 may be constituted, if so desired, by a coil possessing very closely wound turns'the inside of which is'subject to the circulation of a convenient kind of cooling liquid, or the like. As to the rest the entire apparatus could be plunged and immersed in a vat filled with oil or an analogous liquid.

In Fig. 2 the electrodes possess the shape of flat rings; there being shown but a part of the magnetic circuit 5, and it has been supposed by way of modification that the apparatus com prises no control electrode (or grid),cathode 2 being in this case shown as being surrounded by two anodes 8, 3, insuch a manner'that its whole surface is rationally utilized for the purpose of electron emission. The said two anodes are as depicted in Fig. 2, but one anode may" be provided, and also additional control electrodes (grids) maybe furnished, and so on.

Both of'the arrangements h reihbefore referred to are only given by way of example, and they are capable of numerous variations and modifications For example, magnetic circuit 5 maybe only partly closed, especi'ally when the frequency of the induced current flowing through 6 has a'high value.

Having described my invention, what I claim is:

1. In a thermionic device the combination of a sealed container in the shape of a torus having therein a plurality of annular electrodes, and a magnetic core. extending through the opening of said torus and having thereon a winding arranged in inductive relation to said electrodes and adapt ed to be traversed by fluctuating currents whereby one or more of said electrodes may be heated by induction. I v l 2. In a thermionicdevice the combination of a sealed annular container, cylindrical cathode and plate electrodes concentrically disposed and in spaced relation to each other and to said con-- tainer, a magnetic core extending through the opening of said container and ininductive r'ela-- tion to said electrodes, and means on said core to generate a varying magnetic field whereby one of said electrodes is heated by induction.

3. In a thermionic device the combination of a sealed container in the form of a torus, a plural ity of concentric cylindrical electrodes therein,

i and a magnetic core arranged in the opening in said torus in inductive relation'to said electrodes and 'havin'g a winding thereon, whereby when said winding is traversed by'fiuctuating current at least one of said electrodes will be heated by I induction, another of said electrodes containing.

slits to prevent it from'being tion of said magnetic core.

4. In a thermionic device, the combination of an annular sealed container having a plurality of annular electrodes therein, and means comprising a member extending through the opening of said annular container and cooperating with said conelectrodes to heat the said heated by the acelectrode.

5. In a thermionic device, the combination of an annular sealed container having a plurality of electrodes therein, a transformer core extending through the-opening of said annular container, and a coil serving as the primary and the electrode to be heated serving as the secondary of may bev the transformer, whereby said electrode heated by induction.

6. In a hot-cathodeelectron-discharge device,

an anode, a cathode, an auxiliary electrode'for controlling the flow of electrons in the discharge space'between said cathode and anode, means for heating said cathode to a temperature of electron emission, said means tuating magnetic field adjacent to said cathode, and a magnetic screen substantially preventing said flux from interfering with the electron discharge betweensaid cathode and anode.

7. In a hot-cathode electron-discharge device, an anode, a cathode, an auxiliary electrode for controlling the electron flow in the discharge space between said cathode and'a'no'de, and means for producing a magnetic flux for inductively heating said cathode, said means comprising a core of magnetic material inductively interlinked with the heating-current-flow paths in said;

cathode.

8. In a hot-cathode electron-discharge device,

vmeans for inducing a magnetic flux, a'catho'de member constituting a closed current path interiinked with the flux induced by said means, an

anode co-"operating with said cathode, and means for segregating the major portion of the flux interlinked with said cathode from the electron-dis charge space between said cathode andanode.

. 9. Inan electron-discharge device, a pair of annular electrodes constituting an electron-disdischarge space, and means for producing a magnetic'flux, all of the flux 10. In a hot-cathode electron-discharge tube,- an anode, a cathode, and core associated with said cathode core constituting a low-reluctance fluxpath I produced by saidymeans being interlinked with both-of said electrodes;

producing a fiuc chargespace, a hermetic envelope enclosing said a segregating the inducingflux from the discharge space between said cathode and anode. K

11. In anelectron-discharge device, a pair of electrodes constituting an ele'ctron dis'charge path, one of said electrodes comprising a substantiallyclosed-circuited secondary transformer winding, and a magnetic core constituting a 'sub-' stantially closed-circuited magnetic flux path interlinked with said winding. 12. A hot-cathode device comprising atoroidal container, an annular anodeconcentrically disposed in said container, an annular cathode'simi-' larlydisposed within said container, a laminatediron core passing'through the central opening of saidtoroidal container, and a coil for inducingi,

an alternating flux in said core, said cathode 0on5 stitutingaclosed-circuited winding surrounding said core.

13. In a thermionic device,-a cylindrical cathode, a heating device therefon'and an evacuated envelope electrically separating the heating device from the cathode, the heating device he wherebythe heating ing external to saidenvelope device is readily replaceable.

JOSEPH BerHENon in j 

